How severe is CVE-2020-9307?

CVE-2020-9307 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over an adjacent network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2020-9307 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (43rd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-9307?

CVE-2020-9307 affects Belden Hirschmann Hios. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2020-9307?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2020-9307 published?

CVE-2020-9307 was published on 2021-02-11 and last updated on 2026-06-17.

CVE-2020-9307

CVE-2020-9307 is a medium-severity vulnerability in Belden Hirschmann Hios with a CVSS 3.x base score of 6.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-835.

Key facts

Severity: Medium (CVSS 3.x base score 6.5)
CVSS v2: 6.1
EPSS exploit prediction: 1% (43rd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-835
Affected product: Belden Hirschmann Hios
Published: 2021-02-11
Last modified: 2026-06-17

Description

Hirschmann OS2, RSP, and RSPE devices before HiOS 08.3.00 allow a denial of service. An unauthenticated, adjacent attacker can cause an infinite loop on one of the HSR ring ports of the device. This effectively breaks the redundancy of the HSR ring. If the attacker can perform the same attack on a second device, the ring is broken into two parts (thus disrupting communication between devices in the different parts).

Frequently asked questions

What is CVE-2020-9307?: Hirschmann OS2, RSP, and RSPE devices before HiOS 08.3.00 allow a denial of service. An unauthenticated, adjacent attacker can cause an infinite loop on one of the HSR ring ports of the device. This effectively breaks the redundancy of the HSR ring. If the attacker can perform the same attack on a second device, the ring is broken into two parts (thus disrupting communication between devices in the different parts).
How severe is CVE-2020-9307?: CVE-2020-9307 has a CVSS 3.x base score of 6.5, rated medium severity. It is exploitable over an adjacent network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2020-9307 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (43rd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-9307?: CVE-2020-9307 affects Belden Hirschmann Hios. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2020-9307?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2020-9307 published?: CVE-2020-9307 was published on 2021-02-11 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:o:belden:hirschmann_hios:*:*:*:*:*:*:*:*

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